Radio frequency noise management

ABSTRACT

A payment terminal has a clock management unit for providing clock signals to components of the payment terminal. The payment terminal also has a wireless communication interface for communicating wireless signals. A processing unit of the payment terminal may monitor clock signals provided by the clock management unit and determine a phase and frequency difference between a clock signal provided to a component producing RF noise and a clock signal provided to a wireless communication interface of the payment terminal. When RF noise present in the received wireless signal falls below a threshold, the processing unit may sample the received wireless signal.

BACKGROUND

Radio frequency (“RF”) communication devices are capable ofcommunicating wireless signals with other RF communication devices, andmay be used in various transactions, such as payment transactions. An RFcommunication device may have an antenna and related circuitry forreceiving and transmitting wireless signals from another RFcommunication device. The RF communication devices may communicatewireless messages using various RF communication protocols, such as nearfield communication (“NFC”) and Bluetooth. A first RF communicationdevice may generate a wireless carrier signal at a suitable frequency,such as 13.56 MHz, 2.4 GHz, etc., and transmit that signal over itsantenna. When the antenna of a second RF communication device is withinrange of the antenna of the first RF communication device, the twodevices may communicate wirelessly.

The RF communication devices may communicate data by applying additionalenergy to the carrier signal to modulate the signal at a suitablefrequency, depending upon the communication protocol. The additionalenergy may modulate an amplitude, frequency, or phase the carrier signalat the suitable frequency. A second RF communication device mayinterpret modulation of the amplitude, frequency, or phase of thecarrier signal at the frequency as data from the first RF communicationdevice, such as binary data bits. In some cases, the RF communicationdevices may exchange modulated signals across a number of differentsub-frequencies within one or more wireless communication frequencybands.

Signals exchanged between the RF communication devices may experience RFnoise that interferes with underlying wireless data signal. Too muchnoise in a RF signal can distort the signal so that a RF communicationdevice cannot detect modulation of the carrier signal, which can lead toerrors in interpreting data carried by the wireless signal. The RF noisemay interfere if it has sufficient amplitude at frequency or harmonicsthat at least partially overlaps with the wireless communicationfrequencies of the RF communication devices.

The RF communication devices may encounter various sources of RF noiseduring operation. Electromagnetic fields may be present in environmentswhere the RF communication devices are operating, and may affectwireless signals. In addition, RF noise may be emitted during operationof electronic circuitry. For example, components of an RF communicationdevice, such as a processor or switching circuitry may emit RF noisewhile operating. The RF noise emitted by the components of the RFcommunication device may have a frequency that overlaps the frequency ofsignals communicated by the RF communication devices. This RF noise canlead to errors in the processing of signals communicated between the RFcommunication devices, resulting in increased processing times, poordata transmission quality, or data loss.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present disclosure, its nature andvarious advantages will be more apparent upon consideration of thefollowing detailed description, taken in conjunction with theaccompanying drawings in which:

FIG. 1 shows an illustrative block diagram of a payment system inaccordance with some embodiments of the present disclosure;

FIG. 2 depicts an illustrative block diagram a power supply, USB hub,merchant terminal and customer terminal of a point-of-sale system inaccordance with some embodiments of the present disclosure;

FIG. 3 depicts an illustrative block diagram of components of themerchant terminal in accordance with some embodiments of the presentdisclosure;

FIG. 4 depicts an illustrative block diagram of components of thecustomer terminal in accordance with some embodiments of the presentdisclosure;

FIG. 5 depicts a non-limiting flow diagram illustrating exemplary stepsof a noise management method optimizing communications of NFC signals ata point-of-sale system in accordance with some embodiments of thepresent disclosure;

FIG. 6 depicts a non-limiting flow diagram illustrating exemplary stepsof a noise management method for optimizing communications of NFCsignals at a point-of-sale system in accordance with some embodiments ofthe present disclosure;

FIG. 7 depicts a non-limiting flow diagram illustrating exemplary stepsof a noise management method for optimizing communications of NFCsignals at a point-of-sale system in accordance with some embodiments ofthe present disclosure;

FIG. 8A depicts a front perspective view of a screen of a customerterminal showing a graphical output on the screen in accordance withsome embodiments of the present disclosure; and

FIG. 8B depicts a front perspective view of a customer terminal showinga graphical output on the screen in accordance with some embodiments ofthe present disclosure.

DETAILED DESCRIPTION

A payment system may have one or more point-of-sale (POS) terminals thatfacilitate payment transactions. As part of these payment transactionsthe POS terminal exchanges information with other devices via wirelessradio frequency (RF) communication techniques, WiFi, Bluetooth classic,Bluetooth low-energy, or NFC. The merchant terminal may exchange paymentinformation and customer information with a customer terminal. Theterminal may receive payment information from a customer's paymentdevice (e.g., from credit card with a magstripe or EMV chip, or aNFC-enabled electronic device) and communicate the payment informationto other devices such as additional local terminals and remote serversof payment service systems and financial institutions. In this manner,the POS terminal communicates and exchanges a variety of information viawireless communication as part of processing payment transactions.

RF noise may be present in electronic signals communicated at the POSterminal, and may be emitted by various components of the POS terminal.The RF noise may occur because of the presence of electromagnetic energythat has a frequency at or near a frequency of a channel used by themerchant terminal or customer terminal to communicate a wireless signal.Further, wireless signals may experience noise because of interferencefrom various sources of RF noise in the environment around the POSterminal. All such RF noise can affect wireless RF communication betweenthe POS terminal and other devices.

Although RF noise may generally be present in signals produced andcommunicated as part of operations of the POS terminal, the RF noise canbe managed to reduce the noise and thus increase the signal to noiseratio. For example, effects of RF noise on processing of wireless RFsignals can be minimized by processing a received RF signal at timeswhen RF noise levels are low, such as below a threshold noise level. Inaddition, RF noise emitted by other components of the POS terminaloperating at a frequency that overlaps with the RF communicationfrequency may be reduced by modifying the components' operatingfrequency to a frequency that is outside the RF frequency until RFcommunication is completed.

Instructions stored in memory at the POS terminal may provide steps foroptimizing noise source behavior for RF communication. One or moreprocessing units of the POS terminal can execute the instructions tocontrol a clock management unit that generates clock signals andprovides them to components of the POS terminal. The instructions can beexecuted to compare characteristics of the signals (e.g., phase,amplitude, frequency, etc.) to identify a noise threshold, and toprocess communications at times when noise falls below the threshold.The instructions also can be executed to reduce effects of noise onwireless communications by modifying operating frequencies of componentsthat emit RF noise during wireless communications. The instructions maybe executed to modify operating frequencies of the RF noise-emittingcomponents by modifying clock signals provided to the components, and toreturn the operating frequency of the noise-emitting component to itsinitial operating frequency when wireless communication has beencompleted. The operation of components that emit RF noise may also bemodified in other ways, such as by modifying the operation of the RFemitters during wireless communications. Reduced sets of operations suchmay be performed to avoid operations that result in large levels of RFnoise emissions.

FIG. 1 depicts an illustrative block diagram of a payment system 1 inaccordance with some embodiments of the present disclosure. In oneembodiment, payment system 1 includes a payment device 10, paymentterminal 20, network 30, and payment server 40. In an exemplaryembodiment, payment server 40 may include a plurality of serversoperated by different entities, such as a payment service system 50 anda bank server 60. These components of payment system 1 facilitateelectronic payment transactions between a merchant and a customer.

The electronic interactions between the merchant and the customer takeplace between the customer's payment device 10 and the merchant'spayment terminal 20. The customer has a payment device 10 such as acredit card having magnetic stripe, a credit card having an EMV chip, ora NFC-enabled electronic device such as a smart phone running a paymentapplication. The merchant has a payment terminal 20 such as a paymentterminal or other electronic device that is capable of processingpayment information (e.g., encrypted payment card data and userauthentication data) and transaction information (e.g., purchase amountand point-of- purchase information), such as a smart phone or tabletrunning a payment application. The payment terminal 20 may include morethan one payment terminal device, such as when the payment terminalcomprises a merchant terminal and a customer terminal for processingpayment information.

In some embodiments (e.g., for low-value transactions or for paymenttransactions that are less than a payment limit indicated by a NFC orEMV payment device 10) the initial processing and approval of thepayment transaction may be processed at payment terminal 20. In otherembodiments, payment terminal 20 may communicate with payment server 40over network 30. Although payment server 40 may be operated by a singleentity, in one embodiment payment server 40 may include any suitablenumber of servers operated by any suitable entities, such as a paymentservice system 50 and one or more banks of the merchant and customer(e.g., a bank server 60). The payment terminal 20 and the payment server40 communicate payment and transaction information to determine whetherthe transaction is authorized. For example, payment terminal 20 mayprovide encrypted payment data, user authentication data, purchaseamount information, and point-of-purchase information to payment server40 over network 30. Payment server 40 may determine whether thetransaction is authorized based on this received information as well asinformation relating to customer or merchant accounts, and responds topayment terminal 20 over network 30 to indicate whether or not thepayment transaction is authorized. Payment server 40 may also transmitadditional information such as transaction identifiers to paymentterminal 20.

Based on the information that is received at payment terminal 20 frompayment server 40, the merchant may indicate to the customer whether thetransaction has been approved. In some embodiments such as a chip cardpayment device, approval may be indicated at the payment terminal, forexample, at a screen of a payment terminal. In other embodiments such asa dedicated customer terminal, smart phone, or watch operating as a NFCpayment device, information about the approved transaction andadditional information (e.g., receipts, special offers, coupons, orloyalty program information) may be provided to the NFC payment devicefor display at a screen of the smart phone or watch or storage inmemory.

FIG. 2 depicts an illustrative block diagram of a payment system 100 inaccordance with some embodiments of the present disclosure. In oneembodiment, payment system 100 includes a power supply 102, USB hub 104,USB connector 106, USB connector 108, merchant terminal 110, andcustomer terminal 112. These components of point-of-sale system 100facilitate electronic payment transactions between a merchant and acustomer.

In an embodiment, the power supply 102 may connect to an AC power sourceand convert the AC voltage into a DC voltage for use by the componentsof the payment system 100. A DC voltage (e.g., 12 volts) may be providedto the USB hub 104. USB hub 104 may convert the received DC voltage intoa plurality of DC voltages for use in powering circuitry of the USB hub104. The USB hub 104 allows for the merchant terminal 110 to communicatewith a plurality of other USB peripherals, such as a receipt printer,cash drawer, barcode scanner, scale, keyboard, USB-Ethernet dongle/USBMiFi, and other similar peripheral devices. As described herein, the USBhub 104 may also include power supply circuitry that selectively allowsthe USB hub to provide a power supply signal (e.g., a 12V signal) tomerchant terminal 110 via USB connector 106, and via power supplycircuitry of merchant terminal 110 and USB connector 108, to customerterminal 112.

The electronic interactions between the merchant and the customer maytake place between the merchant terminal 110 and the customer terminal112. In one embodiment, the merchant terminal 110 supports aninteractive computing device that is capable of processing paymentinformation (e.g., encrypted payment card data and user authenticationdata) and transaction information (e.g., purchase amount andpoint-of-purchase information) with the customer terminal 112 and aremote payment server (not depicted). The merchant terminal 110 mayinclude a plurality of interfaces as described herein in order toreceive and provide power, to communicate with the customer terminal 112and other devices such as a remote payment server, and to physicallyinterface with other components such as the customer terminal 112. Theinteractive computing device of the merchant terminal 110 may executethe software instructions of a point-of-sale application to manage userinteractions with a merchant, communications with the customer terminal112, and communications with remote payment servers. The merchant isprovided an interface through which the merchant can enter selections ofpurchased items, access customer information (e.g., loyaltyinformation), check inventory, calculate taxes and fees, and otherwiseperform necessary customer service and transaction steps.

Electromagnetic noise, such as RF noise may be present as a result ofoperation of the various devices in FIG. 2, including power source 102,USB hub 104, USB connector 106, USB connector 108, merchant terminal110, customer terminal 112, and other components. For example, RF noisemay be emitted when current is supplied to USB hub 104 from power source102. Power supplied via USB connector 106 also can result in RF noiseemission. In addition, noise may be produced and emitted by virtue ofoperations of the merchant terminal 110 and customer terminal 112, suchas during processing operations, generation of internal power sources,and communications via USB connector 108. The RF noise may occur at anumber of frequencies and harmonics thereof, including within frequencyranges used by the merchant terminal 110 and customer terminal 112during wireless RF communications (e.g., NFC, Bluetooth, etc.). As aresult, such noise can have detrimental effects on signals communicatedby the merchant terminal 110 and customer terminal 112. If the noisecauses sufficient distortion of the wireless signals communicated by themerchant terminal 110 and customer terminal 112, the signal to noiseratio of the wireless transmission may be reduced and data processingerrors may occur at these devices. This may lead to increasedtransaction processing times or failures of transactions. As describedin greater detail below, in some embodiments, noise managementinstructions stored in memory at the merchant terminal 110 and customerterminal 112 may be executed to limit the impacts of noise in order tooptimize wireless communications from the merchant terminal 110 andcustomer terminal 112.

The customer terminal 112 may operate as a payment terminal thatreceives payment information from a customer, and may provide a varietyof interfaces to interact with the merchant terminal 110 and a customer.A user interface of the customer terminal 112 may allow the user tointeract with the customer terminal 112 in order to interact with themerchant (e.g., select items for purchase, answer queries, confirmpurchases, provide PINs and signatures, etc.), receive paymentinformation (e.g., from a swipe card, chip card, or NFC-enabled paymentdevice) from a customer, communicate with the merchant terminal 110(e.g., wirelessly or via USB connector 108), receive power from merchantterminal 110 (e.g., via USB connector 108), and physically attach to themerchant terminal 110 (e.g., via connecting enclosures of each of thecustomer terminal 112 and the merchant terminal 110).

FIG. 3 depicts a block diagram of an example merchant terminal 110 inaccordance with some embodiments of the present disclosure. Althoughparticular components are depicted in a particular arrangement in FIG.3, it will be understood that merchant terminal 110 may includeadditional components, one or more of the components depicted in FIG. 3may not be included in merchant terminal 110, and the components ofmerchant terminal 110 may be rearranged in a variety of suitablemanners. In an exemplary embodiment, the merchant terminal 110 maycomprise a first USB interface 202, a second USB interface 203, a powermanagement device 204, a USB control circuit 206, a processing unit 208,a user interface 210, an audio device 212, a debug module 214, a wiredinterface 216, a wireless interface 218, and a memory 220.

Processing unit 208 of merchant terminal 110 may include a processorcapable of performing the processing functions of the merchant terminal110 as described herein, and may be embodied by any suitable hardware,software, memory, and circuitry as is necessary to perform thosefunctions. Processing unit 208 may include any suitable number ofprocessors, and may perform the operations of merchant terminal 110based on instructions in any suitable number of memories and memorytypes. In an example embodiment, the processing unit 208 may be aSystem-on-Chip (SoC) processor having a dual-core processor. Inaddition, in some embodiments, processing unit 208 of merchant terminal110 may include clock management hardware, such as one or more chips formanaging clock signals provided to the components of the merchantterminal. For example, in some embodiments, the processing unit 208 mayreceive a clock source signal and generate and provide clock signalssuch as a switching regulator clock signal, NFC clock signal, and aprocessing unit clock signal. The processing unit 208 may performadditional clock signal management functions for achieving thefunctionality described herein.

Further, the processing unit 208 may emit RF noise as part of itsoperations. A frequency of the RF noise may correspond to a frequency ofone or more clock source signals provided to the processing unit 208 tocontrol operations of the processing unit 208, and harmonics thereon. Inthis regard, the processing unit may operate at an operating frequencythat corresponds to the clock signal frequency provided to theprocessing unit 208. An operating frequency of the processing unit 208may thus be modified by modification to one or more clock signalsprovided to the processing unit 208. RF noise emitted by the processingunit 208 may similarly be modified based on modification to theoperating frequency of the processing unit 208.

Processing unit 208 may execute instructions stored in memory 220 ofmerchant terminal 110 (e.g., noise management instructions 224) tocontrol the operations and processing of merchant terminal 110, andmemory 220 may also store information necessary for the operation ofmerchant terminal 110. As used herein, “memory” may refer to anysuitable tangible or non-transitory storage medium. Examples of tangible(or non-transitory) storage media include disks, thumb drives, andmemory, etc., but does not include propagated signals. Tangible computerreadable storage medium include volatile and non-volatile, removable andnon-removable media, such as computer readable instructions, datastructures, program modules or other data. Examples of such mediainclude RAM, ROM, EPROM, EEPROM, SRAM, flash memory, disks or opticalstorage, magnetic storage, or any other non-transitory medium thatstores information that is accessed by a processor or computing device.In an example embodiment, memory 220 may include a flash memory and aRAM memory (e.g., a 16 GB eMMC NAND flash and a 2 GB LPDDR3 RAM).

First USB interface 202 and second USB interface 203 may provide forconnection of other devices or components to the merchant terminal 110as appropriate. Although any type of USB connector and interface may beused in accordance with the present disclosure, in an embodiment each offirst USB interface 202 and second USB interface 203 may be a USB type Breceptacle for interfacing with a type B connector of a USB connector(e.g., USB connector 106 or 108, for connecting to USB hub 104 orcustomer terminal 112). In an embodiment first USB interface 202 andsecond USB interface 203 may be interchangeable, such that merchantterminal 110 may function in an identical manner regardless of which ofthe USB interfaces is coupled to USB hub 104 or customer terminal 112.In some embodiments (not depicted in FIG. 3), the merchant terminal 110may include additional interfaces, such as additional USB ports,Lightning, Firewire, Ethernet, etc.

Although power may be provided to merchant terminal 110 in any suitablemanner, in an embodiment, DC power may be provided from USB hub 104 whenit is connected to the merchant terminal via first USB interface 202 orsecond USB interface 203. A USB control circuit 206 may includecircuitry for interacting with the USB hub 104 to receive the incomingDC power signal and to distribute that signal to other components of themerchant terminal 110 (e.g., via power management device 204) and to thecustomer terminal 112 (e.g., via the other USB interface of first USBinterface 202 and second USB interface 203). A power management device204 (e.g., a discrete power management integrated circuit) may receivepower provided from USB hub 104 through one of the USB interfaces (firstUSB interface 202 or second USB interface 203) and USB control circuit206, and may perform functions related to power requirements of a hostsystem (e.g., DC to DC conversion, battery charging, linear regulation,power sequencing and other miscellaneous system power functions).

In some embodiments, the power management device 204 may includeswitching regulator hardware for modifying power signals provided to theresources and components of merchant terminal 110. In some embodiments,the switching regulator hardware may be various types of switchingregulators, such as a buck, boost, or other types of switchingregulator. The switching regulator hardware may boost voltage providedfrom the USB hub 104 before providing it to other components of themerchant terminal 110. As a result of such modification, the switchingregulator hardware may emit noise at various frequencies, includingnoise at frequencies in RF frequency bands that may affect RFcommunication signals transmitted and received by the merchant terminal110. In some embodiments, the merchant terminal 110 may comprise one ormore switching regulators, each of which may emit RF noise or noise inother frequency bands as part of its operations. As described furtherbelow, one or more processors (e.g., processing unit 208) of themerchant terminal 110 may execute instructions to compensate for RFnoise emitted by the switching regulator hardware by optimizing andcoordinating operations of switching regulator hardware and othercomponents of the merchant terminal 110.

Merchant terminal 110 may also include a user interface 210. Userinterface 210 may provide various interfaces and outputs to the merchantterminal 110 to be viewed by a merchant. An example user interface 210may include hardware and software for interacting with a user, such as atouchscreen interface, voice command interface, keyboard, mouse, gesturerecognition, any other suitable user interface, or any combinationthereof. In one embodiment, the user interface 210 may be a touchscreeninterface that displays an interactive user interface for programs andapplications such as a point-of-sale application running on the merchantterminal 110. The user interface 210 may comprise other components inother embodiments.

In some embodiments, the user interface 210 may be positioned adjacentto components of the merchant terminal 110 configured to communicatewireless signals. The user interface 210 may emit RF noise as part ofits operation, which may cause distortion of RF signals sent andreceived by the wireless interface 218, such as when one or morefrequency bands of the RF noise overlaps one or more RF communicationfrequency bands. In some embodiments, a frequency of the noise emittedby the user interface 210 may correspond to an operating frequency ofthe user interface 210. For example, when the user interface 210 isimplemented as a touchscreen interface, the touchscreen may beconfigured to operate (e.g., provide outputs and receive user inputs) atan initial operating frequency, such as approximately 50-100 Hz. Suchinitial operating frequency may be based on a clock signal provided atan initial clock frequency (e.g., from a clock management unit coupledto the processing unit 208). This initial clock frequency may cause theuser interface 210 to perform operations at the initial operatingfrequency: that is, the initial operating frequency of the userinterface 210 may be based on the initial clock frequency provided tothe user interface 210. In this regard, one or more frequency bands ofthe noise emitted by the user interface 210 when operating at theinitial operating frequency may overlap one or more RF communicationfrequency bands of RF communication interfaces of the merchant terminal110, such as an NFC frequency or Bluetooth frequency of communicationsfrom wireless interface 218. As will be described further below, theuser interface 210 may be operable to perform operations at a modifiedoperating frequency, such as in response to receiving a modified clockfrequency from the clock management unit (e.g., in response tomodification by the processing unit 208 or clock management unit 222).Such modified operations may result in the user interface 210 emittingnoise at one or more modified noise frequencies. In some embodiments,none of the one or more modified noise frequencies may overlap any ofthe one or more RF communication frequencies of the merchant terminal110. Other modifications to operations of the user interface 210 may beperformed in other embodiments, including by techniques other thanmodifying an operating frequency of the user interface 210.

Merchant terminal 110 may also include an audio device 212. Audio device212 may provide audio for the merchant terminal 110. An example audiodevice 210 may comprise an audio amplifier and a speaker for providingappropriate audio for the merchant terminal 110. The merchant terminal110 may comprise other components in other embodiments.

Merchant terminal 110 may also include a debug module 214. In anembodiment, a debug module may provide an interface and processing forperforming debug operations (e.g., by a technician utilizing a debugdevice), such as identifying and removing defects that prevent correctoperation of the merchant terminal 110 and the various componentsthereof. In some embodiments, the functionality of debug module 214 mayonly be initiated in response to a predetermined self-test input, suchthat the debug interface is not externally accessible through acommunication interface.

Merchant terminal 110 may also include a wired interface 216, which mayinclude a suitable interface for wired communication, such as USB,Lightning, FireWire, Ethernet, any other suitable wired communicationinterface, or any combination thereof, to perform, for example, thewired communication with other devices of the payment system 100 andpayment servers (e.g., via a secure internet connection).

Merchant terminal 110 may also include a wireless communicationinterface 218. The wireless communication interface 218 may includesuitable hardware and software for providing a wireless communicationinterface such as radio frequency (RF), Bluetooth classic, Bluetooth lowenergy, WiFi, cellular, short message service (SMS), NFC, any othersuitable wireless communication interface, or any combination thereof.In an example embodiment, the wireless communication interface 218 mayfacilitate communications between the merchant terminal 110 andperipherals, as well as with payment servers (e.g., via a secureinternet connection).

In some embodiments, wireless communication interface 218 may beconfigured for communicating (e.g., sending and receiving) wirelesssignals at one or more frequencies used for wireless communications. Forexample, signals sent and received at the wireless interface 218 mayinclude signals communicated based on one or more frequencies of therespective protocols described herein, such as an NFC carrier signal ata 13.56 MHz frequency, an 800 kHz NFC data modulation frequency, 2.4 GHzfor Bluetooth classic protocol, Bluetooth channels in a 20-25 MHz band,etc. Each signal may have a phase, amplitude, frequency, modulationmethod, and other characteristics. In some embodiments, wireless signalscommunicated by the merchant device 110 may be communicated based on oneor more other wireless communication frequencies. In addition, thesignals sent and received at the wireless communication interface 218may include RF noise at various frequencies. The RF noise may be presentin signals communicated at various frequencies, including frequenciesthat overlap communication frequency bands of signals sent and receivedat the wireless communication interface 218. RF signals may be receivedat an antenna of the wireless communication interface 218, and may beprovided for processing at the merchant terminal 110, such as byprocessing unit 208. In this regard, various components of the merchantterminal 110 may function as a receive circuit for receiving wirelesscommunications (e.g., NFC, Bluetooth, etc.).

In some embodiments, wireless communication interface 218 may bepositioned approximately adjacent to or in close proximity to the userinterface 210. As described above, the user interface 210 may emit RFnoise across various frequencies as part of its operation. Such RF noisecan interfere with communication of signals at the wirelesscommunication interface 218 when one or more noise frequencies overlapone or more communication frequencies of the merchant terminal 110.According to the techniques described herein, noise frequency bands ofnoise emitted by components of the merchant terminal 110, such as theuser interface 218, can be shifted during periods when communicationsare sent or received at the wireless communication interface 218 so thatno overlap of such frequencies occurs.

Clock management unit 222 may include software, hardware or variouscombinations thereof for generating and managing clock signals providedto various components of the merchant terminal 110, such as to a clockinput pin of various components of the merchant terminal 110. In someembodiments, the clock management unit 222 may be implemented as one ormore chips, and may comprise suitable logic for generating and providingclock signals as desired. Exemplary clock signals generated by the clockmanagement unit include one or more clock signals provided to one ormore switching regulators, a wireless communication interface 218, andprocessing unit 208. Each clock signal provided by the clock managementunit 222 may have a desired phase, amplitude, frequency, and duty cycle.In addition, the clock management unit 222 may be configured forreceiving a clock source signal, such as from the processing unit 208,and to generate and provide one or more clock signals based on the clocksource signal.

Noise management instructions 224 may be stored in memory 220 and mayinclude instructions for optimizing communication of wireless signalsand for coordinating operations between a wireless communication sourceand a RF noise source of the merchant terminal 110. The noise managementinstructions 224 may include instructions for controlling operations ofessentially any or various combinations of resources of the merchantterminal 110 to achieve the optimization and coordination operationsdescribed herein, and may include instructions for performing varioustasks described herein simultaneously or at various times. In addition,functionality ascribed to the noise management instructions 224 may bedistributed among other instructions stored in memory 220, and may beimplemented using software, firmware, hardware, or various combinationsthereof.

Noise management instructions 224 may include instructions forcontrolling a clock management unit of the merchant terminal 110 togenerate a plurality of clock signals. In some embodiments, theplurality of clock signals may include various types of clock signalsprovided to components or resources of the merchant terminal 110. Forexample, clock signals that may be generated by the clock managementunit of merchant terminal 110 can include a switching regulator clocksignal, an NFC clock signal, and a processing unit clock signal. Each ofthe plurality of clock signals generated by the clock management unit inresponse to execution of noise management instructions 224 may have aphase, frequency, amplitude, and duty cycle, and may be controlled orconfigured as described herein. In some embodiments, other signals inaddition to the system described herein may be generated based oninstructions 224.

Noise management instructions 224 may include instructions forgenerating a switching regulator clock signal. In some embodiments, oneor more switching regulators of the merchant terminal 110 may emit RFnoise. The RF noise may be based on an operating frequency of the one ormore switching regulators. By controlling a clock signal provided to theone or more switching regulators, a clock management unit (e.g.,processing unit 208 executing noise management instructions 224) of themerchant terminal 110 may be configured to identify RF noise. Noisemanagement instructions 224 may include instructions for providing theswitching regulator clock signal to the one or more switching regulatorsof the merchant terminal 110. The switching regulator clock signal mayhave a phase and frequency, and in some embodiments, the same switchingregulator clock signal may be provided to multiple switching regulatorsof the merchant terminal 110. In this regard, each of the switchingregulators of the merchant terminal 110 may operate based on the sameclock signal, which may have a phase, frequency, amplitude, and dutycycle. In other embodiments, different clock signals may be provided todifferent switching regulators. In this regard, noise managementinstructions 224 may include instructions for determining a phase andfrequency of the switching regulator clock signal that may be used toidentify RF noise.

In some embodiments, noise management instructions 224 may includeinstructions for generating a wireless clock signal such as an NFC clocksignal at the clock management unit 222. The NFC clock signal may beprovided to the processing unit 208 of the merchant terminal 110 and/orthe wireless interface 218 for performing wireless communications (e.g.,at wireless interface 218), such as via RF communication using NFC. Inother embodiments involving different communications methods, thewireless clock signal may correspond to a frequency for thecommunication method (e.g., Bluetooth). In some embodiments, the NFCclock signal may have a phase and frequency that corresponds to a phaseand frequency of one or more wireless communication frequencies of themerchant terminal 110. For example, in some embodiments, the NFC clocksignal may have a phase and frequency that corresponds to a phase andfrequency of the NFC carrier signal (e.g., 13.56 MHz), as modulatedduring communication (e.g., at 800 kHz). A phase and frequency of theNFC clock signal may constitute a baseline phase and frequency fordetecting noise in a received wireless communication signal. Forexample, a received wireless communication signal may have noise on itthat causes variations of the data signal, such that an amplitude,phase, and/or frequency differs from the phase and frequency of the NFCclock signal by an amount greater than a pre-defined threshold. Noisemanagement instructions 224 may include instructions for determiningthat an amount by which the amplitude, phase and/or frequency of the NFCclock signal and the received wireless communication exceeds thethreshold and thus represents unacceptable noise. Note that in someembodiments, noise management instructions may include instructions forreceiving a RF signal at the merchant terminal 110, such as fromwireless communication interface 218. The merchant terminal 110 mayreceive other types of wireless signals in other embodiments, and suchother wireless signals may include RF noise. Noise managementinstructions 224 may include instructions for processing each wirelesssignal received at a merchant terminal 110 according to the techniquesdescribed herein. Other techniques for processing wireless signalsreceived at merchant terminal 110 may be possible in other embodiments.

In some embodiments, noise management instructions 224 may includeinstructions for determining a plurality of possible sampling times forthe received wireless signal (e.g., a received modulated NFC signal)based on a phase and frequency of a clock signal provided to theprocessing unit 208. The processing unit 208 may process data based on afrequency of the clock signal provided to the processing unit 208. Arate at which sampling of the received NFC signal may be may beperformed thus may be determined based on a frequency and phase of aclock signal provided to the processing unit 208, and further based onwhen possible sampling times correspond to times when data is receivedand noise is minimized. As noted above, the wireless communicationsignal received at the merchant terminal 110 may have a phase andfrequency which may be based on a wireless carrier signal phase andfrequency, and a RF noise source may also have a phase and frequency.Thus, the times at which processing unit 208 may perform sampling of thewireless communication signal may be based on a phase and frequency ofthe processing unit clock signal and times when the data of the receivedwireless signal us less likely to be impacted by noise. In this regard,noise management instructions 224 may include instructions foridentifying a plurality of possible sampling times that may be comparedwith time periods during in which noise present in a received wirelesscommunication signal is below a threshold.

Noise management instructions 224 may include instructions foridentifying a noise threshold for determining times at which the noisepresent in a received wireless communication signal is reduced. A noisethreshold may be indicative of a value of noise that may allowprocessing of the wireless communication signal with a desired (e.g.,reduced) number of errors. By processing (e.g., sampling) the receivedwireless communication signal during such times when noise falls belowthe noise threshold, errors in processing the received wireless signalat the processing unit 208 may be reduced. Noise management instructions224 may include instructions for determining a noise threshold based onmeasured or predicted differences between phases and frequencies ofvarious signals at the merchant device 110, but in some embodiments, athreshold may be determined based on a first phase difference and afirst frequency difference. In an exemplary embodiment, the first phasedifference may be based on a difference between a phase of the switchingregulator clock signal and a phase of the NFC clock signal. The firstfrequency difference may be based on a difference between a frequency ofthe switching regulator clock signal and a frequency of the NFC clocksignal. Again, other information may be used to identify a suitablenoise threshold in other embodiments.

Noise management instructions 224 may include instructions foridentifying time periods when RF noise is below a noise threshold. Byidentifying the time periods when a noise value (e.g., an aggregatevalue of RF noise emitted by components such as the one or moreswitching regulators) falls below the threshold, the received wirelesscommunication signal may be sampled for processing at such times at theprocessing unit 208. In this regard, portions of the wirelesscommunication signal sampled for processing at the processing unit 208may have RF noise that is below the noise threshold, reducingnoise-related errors. The noise management instructions 224 may includeinstructions for aggregating RF noise present due to the one or moreswitching regulators and RF noise present in the received wirelesscommunication signal (e.g., as may be received by the NFC receivecircuit at wireless communication interface 218), determining a valueassociated with the RF noise, and comparing it with the threshold. Suchaggregation and comparison may be performed at a desired number of timeperiods, such as based on one or more of the switching regulator clocksignal, NFC clock signal, and processing unit clock signal. In thisregard, the noise management instructions 224 may include instructionsfor identifying a plurality of time periods at which the RF noise fallsbelow the threshold.

Noise management instructions 224 may include instructions for comparingsampling times for the processing unit 208 (e.g., based on theprocessing unit clock signal) with the plurality of time periods duringwhich RF noise is below the noise threshold and identifying the timeperiods which correspond with the sampling times. By comparing timesfrom the plurality of time periods with the plurality of possiblesampling times for the processing unit 208, periods when sampling of thereceived wireless communication signal with RF noise that is below thenoise threshold may be possible. In this regard, the noise managementinstructions 224 may include instructions for causing the processingunit 208 to perform sampling of the signal at time periods from theplurality of time periods that correspond to sampling times from theplurality of possible sampling times. In this regard, the receivedwireless communication signal sampled by the processing unit 208 may beprocessed at times during which RF noise present at the merchant device110 is below the noise threshold. Other techniques for processing thereceived wireless communication signal during times when RF noise at themerchant device 110 is below a noise threshold may be possible in otherembodiments.

In some embodiments, the noise management instructions 224 may includeinstructions for coordinating operations between a wirelesscommunication source of the merchant terminal 110 and a source of RFnoise within the merchant terminal 110. By coordinating operations thewireless communication components of the merchant terminal 110 andvarious sources of RF noise within the merchant terminal 110, signalquality and communication efficiency of wireless communication signalscommunicated by the merchant terminal 110 may be improved. Processingunit 208 may execute noise management instructions 224 to perform suchcoordination according to the techniques described herein, but it willbe understood that similar techniques for coordinating operations of thecomponents of the merchant terminal 110 for management of RF noise maybe possible in other embodiments.

Noise management instructions 224 may include instructions formonitoring operation of wireless communication resources of merchantterminal 110, such as clock signals provided to processing unit 208 andsignals received via wireless communication interface 218 to identifyperiods of time during which wireless communications are occurring. Forexample, operations of sources of RF noise may be modified or altered asdesired in order to modify frequency bands of RF noise emitted by the RFnoise source. In this regard, an operating frequency of one or more ofthe noise sources may be modified by modifying a clock signal providedto the one or more noise sources. In this regard, modification of theclock signal frequency may result in modification of a frequency of theRF noise. RF noise thus may be shifted to one or more frequency bandsthat do not overlap with any portion of the wireless communicationfrequency band in use at the merchant terminal.

Noise management instructions 224 may include instructions foridentifying an operating frequency of one or more RF noise sources, suchas based on a clock signal provided to the RF noise source. Resources ofthe merchant terminal 110 may emit RF noise during operation. RF noisemay be emitted by processing unit 208, user interface 218, one or moreswitching regulators, or other components that operate at a frequency. Afrequency of RF noise emitted by the RF noise source may be based uponan operating frequency of the noise source, which in turn may be basedupon a frequency of a clock signal provided to the RF noise source. Inthis regard, one or more frequencies of RF noise may correspond to oneor more operating frequencies of the RF noise source. An operatingfrequency may be modified by modifying a frequency of a clock signalprovided to the RF noise source (e.g., from clock management unit 222).In this regard, the noise management instructions may includeinstructions for modifying one or more frequencies of RF noise bymodifying a clock signal frequency of the one or more RF noise sources.

Noise management instructions 224 may include instructions fordetermining that the merchant terminal 110 is communicating at one ormore wireless communication frequencies. Noise management instructions224 may include instructions for identifying periods when the merchantterminal is communicating wirelessly, such as based on characteristics(e.g., phase, frequency, etc.) of one or more clock signals provided toprocessing unit 208. For example, wireless communication may beoccurring when a clock signal frequency provided to the wirelesscommunication interface corresponds to a wireless communicationfrequency, when a transmission voltage or current is being provided to atransmit signal, or when the processing unit is performingcommunications functions.

Noise management instructions 224 may include instructions fordetermining that one or more frequencies of RF noise emitted by a RFnoise source overlap at least a portion of RF communication frequenciesthat the merchant terminal 110 is using for wireless communication. Forexample, noise management instructions 224 may compare one or more RFnoise frequencies with frequencies used in various wirelesscommunication protocols at the merchant terminal 110, such as Bluetoothchannel frequency bands (e.g., indicated on a Bluetooth channel mapstored in memory 220), NFC frequencies, etc. If a frequency of RF noisefalls within a range of frequencies for wireless communication, thenoise management instructions may determine that a frequency of the RFnoise overlaps at least a portion of the one or more wirelesscommunication frequencies. Other techniques for determining whether anRF noise frequency overlaps one or more wireless frequency bands arepossible in other embodiments.

Noise management instructions 224 may include instructions for modifyingan operating phase or frequency of one or more RF noise sources. The oneor more RF noise sources may normally operate at an initial operatingfrequency. For example, a processing unit 208 may receive an initialclock signal that causes the processing unit 208 to perform processingoperations at an operating frequency that corresponds to the initialclock signal frequency. In an embodiment, user interface 218 may receivean initial clock signal that has an initial clock signal frequency andmay perform operations of user interface 218 (e.g., touchscreen 218) atan operating frequency that corresponds to the initial clock signalfrequency. Note that one or more clock signals may be provided to theone or more RF noise sources, and in some embodiments, such clocksignals may be provided by clock management unit 222 of merchantterminal 110. As noted above, an operating frequency of an RF noisesource may correspond to a frequency of RF noise emitted by the RF noisesource. In this regard, an initial operating frequency of the RF noisesource may be modified, such as by modifying an initial clock signalfrequency provided to the RF noise source. A frequency of RF noiseemitted by the RF noise source thus may be modified based on themodified operating frequency.

In some embodiments, operations that are performed by the RF noisesource may be a standard set of operations, and the operations may bemodified to a reduced set of operations to limit RF noise emitted by theRF noise source. In some embodiments, noise management instructions 224may include instructions for causing the one or more RF noise sources toperform a modified (e.g., reduced) set of operations, such as byreducing power for certain operations or foregoing normal processingoperations. In some embodiments, the reduced set of operations maycorrespond to operations that are possible at the modified operatingfrequency based on receipt of a modified clock signal. In addition,noise management instructions 224 may include instructions fordetermining that the merchant terminal 110 is no longer communicatingwirelessly (e.g., based on monitoring of signals provided to thewireless communication interface 218) and causing one or more RF noisesources to return to performing standard operations. In someembodiments, a clock signal provided to the one or more RF noise sourcesmay return to an initial operating frequency once wirelesscommunications are complete.

FIG. 4 depicts a block diagram of an exemplary customer terminal 112 inaccordance with some embodiments of the present disclosure. Althoughparticular components are depicted in a particular arrangement in FIG.4, it will be understood that customer terminal 112 may includeadditional components, one or more of the components depicted in FIG. 4may not be included in customer terminal 112, and the components ofcustomer terminal 112 may be rearranged in a variety of suitablemanners. In one embodiment, customer terminal 110 may comprise a USBinterface 302, a power management device 304, a debug module 306, anaudio device 308, a user interface 310, a clock management unit 311, amain processing unit 312, a memory 314, a secure enclave 340, a magneticswipe slot 330, an EMV slot 332, and an NFC flex circuit 334.

Clock management unit 311 may include software, hardware or variouscombinations thereof for generating and managing clock signals providedto various components of the customer terminal 112, such as to a clockinput pin of various components of the customer terminal 112. In someembodiments, the clock management unit 311 may be implemented as one ormore chips, and may comprise suitable logic for generating and providingclock signals as desired. Exemplary clock signals generated by the clockmanagement unit include one or more clock signals provided to one ormore switching regulators, a NFC interface 328, and main processing unit312. Each clock signal provided by the clock management unit 311 mayhave a desired phase, amplitude, frequency, and duty cycle. In addition,the clock management unit 311 may be configured for receiving a clocksource signal, such as from the main processing unit 312, and togenerate and provide one or more clock signals based on the clock sourcesignal. Note that, although clock management unit 311 is depicted asbeing coupled to main processing unit 312, the clock management unit 311may be coupled to provide clock signals to various resources of customerterminal 112 to achieve the functionality described herein, including tomain processing unit 312, secure processing unit 316, user interface 310and 318, and NFC interface 328.

Main processing unit 312 of customer terminal 112 may include aprocessor capable of performing the processing functions of the customerterminal 112 as described herein, and may be embodied by any suitablehardware, software, memory, and circuitry as is necessary to performthose functions. Main processing unit 312 may include any suitablenumber of processors, and may perform the operations of customerterminal 112 based on instructions in any suitable number of memoriesand memory types. In an example embodiment, the main processing unit 312may be a System-on-Chip (SoC) processer having a dual-core processor(e.g., a Dual core ARM Cortex A7/A9).

Main processing unit 312 may execute instructions stored in memory 314of customer terminal 112 to control the operations and processing ofcustomer terminal 112, and the memory 314 may also store informationnecessary for the operation of customer terminal 112. In an exampleembodiment, memory 314 may include a flash memory and a RAM memory(e.g., a 16 GB eMMC NAND flash and a 2 GB LPDDR3 RAM). Memory 314 mayinclude instructions (e.g., noise management instructions 315) foroptimizing NFC communication and coordinating operation of RFcommunication sources with RF noise sources at the customer terminal112.

USB interface 302 may provide for a connection to the merchant terminal110 in order to receive power from merchant terminal 110 and tocommunicate with the merchant terminal 110. Although any type of USBconnector and interface may be used in accordance with the presentdisclosure, in an embodiment USB interface 302 may be a USB type Breceptacle for interfacing with a micro USB type B connector of a USBconnector (e.g., USB connector 106 or 108, for connecting to merchantterminal 110). In some embodiments (not depicted in FIG. 4), customerterminal 112 may include additional wired or wireless interfaces such asadditional USB ports, Lightning, Firewire, Ethernet, WiFi, Bluetooth,etc.

Although power may be provided to customer terminal 112 in any suitablemanner, in an embodiment DC power may be provided from merchant terminal110 when it is connected to the customer terminal 112 via the USBinterface 302. A USB control circuit 303 may include circuitry forinteracting with the merchant terminal 110 to receive the incoming DCpower signal and to distribute that signal to other components of thecustomer terminal 112 (e.g., via power management device 304). In someembodiments, USB control circuit 303 may enable additionalfunctionality, such as initiating a reprogramming mode for the customerterminal based on a received voltage at USB interface 302. A powermanagement device 304 (e.g., a discrete power management integratedcircuit) may receive power provided from merchant terminal 110 throughthe USB interface 302 and USB control circuit 303, and may performfunctions related to power requirements of the customer system (e.g., DCto DC conversion, battery charging, linear regulation, power sequencingand other miscellaneous system power functions).

Customer terminal 112 may also include a user interface 310. Userinterface 310 may provide various interfaces and outputs to the customerterminal 112 to be viewed by a customer. An example user interface 310may include hardware and software for interacting with a customer, suchas a touchscreen interface, voice command interface, keyboard, mouse,gesture recognition, any other suitable user interface, or anycombination thereof. In one embodiment, the user interface 310 may be atouchscreen device that displays an interactive user interface for thecustomer to engage in purchase transactions (e.g., select items forpurchase, answer queries, confirm purchases, provide PINs andsignatures, etc.) at the customer terminal 112.

In some embodiments, the user interface 310 may be positioned adjacentto components of the customer terminal 112 configured to performwireless communication. The user interface 310 may emit RF noise as partof its operation, which may cause distortion of signals sent andreceived by the NFC interface 328 when one or more frequency bands ofthe noise overlap one or more communication frequency bands. In someembodiments, a frequency of the noise emitted by the user interface 310may correspond to an operating frequency of the user interface 310. Forexample, when the user interface 310 is implemented as a touchscreeninterface, the touchscreen may be configured to operate (e.g., provideoutputs and receive user inputs) at an initial operating frequency, suchas approximately 50-100 Hz. Such initial operating frequency may bebased on a clock signal provided at an initial clock frequency (e.g.,from a clock management unit 311 coupled to the main processing unit 312and secure processing unit 316). This initial clock signal may cause theuser interface 310 to perform operations at the initial operatingfrequency: that is, the initial operating frequency of the userinterface 310 may be based on the initial clock frequency provided tothe user interface 310. In this regard, one or more frequencies of thenoise emitted by the user interface 310 when operating at the initialoperating frequency may overlap one or more wireless communicationfrequencies of RF communication interfaces of the customer terminal 112,such as an NFC frequency band or Bluetooth frequency band ofcommunications from NFC interface 328. As will be described furtherbelow, the user interface 310 may be operable to perform operations at amodified operating frequency, such as in response to receiving amodified clock signal from the clock management unit (e.g., in responseto modification by the main processing unit 312 or secure processingunit 316). Such modified operations may result in the user interface 310emitting noise at one or more modified noise frequencies. In someembodiments, none of the one or more modified noise frequencies mayoverlap any of the one or more RF communication frequencies of thecustomer terminal 112. Other modifications to operations of the userinterface 310 may be performed in other embodiments, including bytechniques other than modifying an operating frequency of the userinterface 310.

Customer terminal 112 may also include an audio device 308. Audio device308 may provide audio for the customer terminal 112. An example audiodevice 308 may comprise an audio amplifier and a speaker for providingappropriate audio for the customer terminal 112. The audio device 308may comprise other components in other embodiments.

Customer terminal 112 may also include a debug module 306. In anembodiment, a debug module 306 may provide an interface and processingfor performing debug operations (e.g., by a technician utilizing a debugdevice), such as identifying and removing defects that prevent correctoperation of the customer terminal 112 and the various componentsthereof. In an embodiment, debug module 306 may be secured using varioustechniques. Debug module 306 may restrict or reject communications(e.g., a signal) received from the debug module 306 unless thecommunication is from an approved device. For example, instructionsstored in memory, such as memory 314, may include instructions (e.g.,noise management instructions 315) for optimizing NFC communication andcoordinating operation of RF communication sources with RF noise sourcesat the customer terminal 112. In some embodiments, the functionality ofdebug module 306 may only be initiated in response to a predeterminedself-test input, such that the debug interface is not externallyaccessible through a communication interface. In some embodiments, debugmodule 306 may be secured physically, such as by use of a filter, switchor other device. Other techniques for securing debug module 306 may beused in other embodiments.

The secure enclave 340 may be a secure portion of the customer terminal112 that performs critical functionality such as interacting withpayment devices and cryptography, and that stores sensitive informationsuch as cryptographic keys, passwords, and user information. In anembodiment, the secure enclave 340 may be located in a distinct locationof the customer terminal 112 to isolate the secure enclave 340 fromother circuitry of the customer terminal 112 and to allow protectivemeasures (e.g., tamper detection switches, anti-tamper meshes,anti-tamper domes, isolated compartments, etc.) to be installed near andaround the secure enclave 340 (not depicted in FIG. 4). In an exampleembodiment, the secure enclave 340 may be situated at a portion of thecustomer terminal 112 in a manner that provides additional physicalclearance for protective measures.

In an embodiment, the secure enclave 340 may include a secure processingunit 316, a user interface 318, a battery 320, a debug module 322, amagnetic swipe interface 324, a chip card interface 326, and an NFCinterface 328.

Although secure processing unit 316 may be implemented with any suitableprocessor, hardware, software, or combination thereof, in an embodiment,secure processing unit 316 may be implemented as microcontroller unit(MCU). Secure processing unit 316 may perform transaction processing andcryptographic operations, based on instructions and information (e.g.,customer data, encryption keys, etc.) stored in a memory of secureprocessing unit 316 (not separately depicted in FIG. 4), which may beany suitable memory as described herein. Secure processing unit 316 maycommunicate with main processing unit 312 in order to receive andrespond to requests for processing of payment information.Communications may be performed using any suitable internal bus andcommunication technique (e.g., UART, SPI, I²C, and GPIO).

The secure enclave 340 of customer terminal 112 may also include abattery 320. In some embodiments, the battery 320 may function as aprimary power source to certain components of the secure enclave 340(e.g., memory storing critical payment, customer, and encryptioninformation), such that when the battery power is removed theinformation is lost. The battery 320 may function in this manner inresponse to a tamper attempt, such that in response to the tamperattempt, the secured information is destroyed.

The secure enclave 340 of customer terminal 112 may also include a debugmodule 322. In an embodiment, a debug module 322 may provide aninterface and processing for performing debug operations (e.g., by atechnician utilizing a debug device) directly with the components of thesecure enclave. In some embodiments, the functionality of debug module322 may only be initiated in response to a predetermined self-testinput, such that the debug interface is not externally accessiblethrough a communication interface.

The secure enclave 340 of customer terminal 112 may also include a userinterface 318. In an embodiment, user interface 318 (e.g., a keypad,touchscreen, etc.) may be located within the secure enclave such thatcertain content is provided to the secure enclave 340 rather than thegeneral processing circuitry of the customer terminal 112. In thismanner, critical information such as PIN numbers, signatures, andpasswords may be provided only to the secure enclave 340 in the firstinstance, and then forwarded to the main processing unit 312 inencrypted or unencrypted form, as required. In some embodiments, theuser interface 318 may emit RF noise during operation in a mannersimilar to that of user interface 310, such as when user interface 318is implemented as a touchscreen. In this regard, operations of userinterface 318 may be controlled using essentially the same or similartechniques as described herein with regard to user interface 310 tooptimize NFC communication or manage noise emitted by one or more RFnoise sources, including user interface 318.

Secure enclave 340 of customer terminal 112 may also include a magneticswipe interface 324, chip card interface 326, and NFC interface 328.Each of these components may include interface circuitry for receivingand processing signals from a payment interface, such as a magneticreader head 330, a chip card slot 332 (e.g., providing power andcommunications to the chip card), and an NFC circuit, components ofwhich may be located on an NFC flex circuit 334 remote from secureenclave 340. For example, instructions stored in memory, such as memory314, may include instructions for disabling secure enclave 340 andlimiting or rejecting communications at magnetic swipe interface 324,chip card interface 326, and NFC interface 328. Other techniques forinterfaces of secure enclave 340 may be used in other embodiments.

In some embodiments, NFC interface 328 may be configured forcommunicating (e.g., sending and receiving) wireless signals atfrequencies used for wireless communications. For example, signals sentand received at the NFC interface 328 may include signals communicatedbased on one or more frequency frequencies of the respective protocolsdescribed herein, such as an NFC carrier signal at a 13.56 MHzfrequency, an 800 kHz NFC data modulation frequency. Each signal mayhave a phase, amplitude, frequency, or other characteristics. In someembodiments, signals may be communicated based on one or more otherwireless communication frequency bands. In addition, the signals sentand received at the NFC interface 328 may include noise coupled thereonat various frequencies. The noise may be present in signals communicatedat various frequencies, including frequencies that overlap communicationfrequency bands of signals sent and received at the NFC interface 328.Signals received at the NFC interface 328 may be provided for processingat the customer terminal 112, such as by secure processing unit 316 ormain processing unit 312. In this regard, various components of thecustomer terminal 112 may function as a receive circuit for receivingwireless communications (e.g., NFC, Bluetooth, etc.).

In some embodiments, NFC interface 328 may be positioned approximatelyadjacent to or in close proximity to the user interfaces 310 and 318. Asdescribed above, the user interfaces 310 and 318 may emit noise invarious frequency bands as part of its operation. Such noise caninterfere with communication of signals at the NFC interface 328 whenone or more noise frequency bands overlap one or more communicationfrequency bands of the customer terminal 112. According to thetechniques described herein, noise frequency bands of noise emitted bycomponents of the customer terminal 112, such as the user interfaces 310and 318, can be shifted during periods when communications are sent orreceived at the NFC interface 328 so that no overlap of such frequencybands occurs.

Noise management instructions 315 may be stored in memory 314 and mayinclude instructions for optimizing communication of wireless signalsand for coordinating operations between a wireless communication sourceand a wireless noise source of the customer terminal 112. In anexemplary embodiment, noise management instructions 315 may operateinclude some or all of the functionality of noise management instruction224, as applied to the particular RF noise sources (e.g., powermanagement device 304, user interface 310, main processing unit 312,secure processing unit 316, user interface 318, and chip card interface326), communication interfaces (e.g., NFC interface 328 and NFC Flex334, a Bluetooth transponder (not depicted), etc.), and controlcircuitry (e.g., CMU 311) of the customer terminal 112.

FIG. 5 depicts a non-limiting flow diagram illustrating exemplary stepsof a noise management method for optimizing communications of NFC signalat a point-of-sale system in accordance with some embodiments of thepresent disclosure. In an embodiment, the steps of FIG. 5 may bedirected to and performed by a merchant terminal 110 or customerterminal 112 for optimizing receipt of a RF signal by sampling thesignal at times when RF noise is below a threshold value. Forsimplicity, the term “payment terminal” may refer to either or acombination of the merchant terminal 110 or customer terminal 112. Inaddition, payment terminal components referenced herein may refer tocorresponding components of either the merchant terminal 110 or customerterminal 112 or various suitable combinations thereof. Further, theoperations below are described in the context of communication using NFCsignals, but it will be understood that communication of RFcommunication signals according to other protocols are possible. It willbe further understood that in some embodiments (not depicted in FIG. 5),identification of times when the RF signal may be sampled and noise isbelow a threshold value may be performed in other manners, as describedherein.

At step 502, a clock source signal may be generated. The clock sourcesignal may be generated by a clock source of the payment terminal, whichmay comprise hardware, software, or various combinations thereof. Insome embodiments, the payment terminal may comprise one or more clocksources. The clock source signal generated at step 502 may provide aclock signal for performing processing operations to one or morecomponents of the payment terminal. Note that the clock source signalmay have a desired phase, frequency, duty cycle, or othercharacteristics for achieving the functionality described herein. Notealso that the clock source signal generated by the clock source may beprovided to various numbers of processing units of the payment terminalin other embodiments. After the clock source of the payment terminal hasgenerated the clock source signal processing may continue to step 504.

At step 504 the clock source signal may be received at a clockmanagement unit (e.g., clock management units 222 or 311) of the paymentterminal, such as when provided from the clock source. In someembodiments, the payment terminal include various types of hardware,software, or various combinations thereof for controlling and managingclock signals provided to one or more of the various components of thepayment terminal. In some embodiments, the clock management unit may beimplemented in hardware and may be in communication with one or moreprocessors, (e.g., processing unit 208, processing unit 312, processingunit 316, etc.), power sources, displays, or other components. The clockmanagement unit may be configured to generate and provide a pluralityclock signals based on receipt of the clock source signal. After theclock management unit receives the clock source signal, processing mayproceed to step 506

At step 506, a plurality of clock signals may be generated at the clockmanagement unit of the payment terminal. In some embodiments, theplurality of clock signals generated by the clock management unit mayinclude various types of clock signals provided to various components ofthe payment terminal. For example, the plurality of clock signals mayinclude a switching regulator clock signal, display clock signals, anNFC clock signal, and a processing unit clock signal. In addition, eachof the plurality of clock signals may comprise various characteristicsas desired. For example, the switching regulator clock signal may havethe first phase and first frequency, the NFC clock signal may have asecond phase and second frequency, the processing unit clock signal mayhave a third phase and third frequency and a display may have a fourthphase and a fourth frequency. In some embodiments, each of the pluralityof clock signals may have different phases, frequencies, amplitudes,and/or duty cycles. After the clock management unit of the paymentterminal has generated the plurality of clock signals, processing maycontinue to step 508.

As step 508 a component clock signal such as the switching regulatorclock signal may be received, such as by one or more switchingregulators of the payment terminal. In some embodiments, the paymentterminal may comprise one or more components that may be configured forperforming the functionality of a switching regulator such as a buck,boost, or other-switching regulator type. Exemplary components of thepayment terminal which may include or embody the functionality of aswitching regulator may include a power management device (e.g., powermanagement device 204, power management device 304, etc.). In thisregard, the switching regulator clock signal may be configured tosynchronize operation of the one or more switching regulators of thepayment terminal based on the switching regulator clock signal orsignals. In addition, the switching regulator clock signal may have afirst phase and first frequency when provided to the one or moreswitching regulators, such that a one or more switching regulatorsoperate at an operating frequency that is based upon the first phase inthe first frequency of the switching regulator clock signal. In thisregard, a frequency of RF noise emitted by the one or more switchingregulators during operation may have a phase and frequency thatcorresponds to the operating frequency of the one or more switchingregulators and harmonics thereof. Thus, the phase and frequency of RFnoise emitted by the one or more switching regulators may correspond tofirst phase and first frequency at which the one or more switchingregulators of the payment terminal operate. After the one or moreswitching regulators has received the switching regulator clock signal,processing may proceed to step 510.

At step 510 a receive circuit of the payment terminal may receive areceived NFC signal. In some embodiments, the payment terminal mayinclude various components for receiving wireless RF signalscommunicated according to various wireless communication techniques(e.g., NFC, Bluetooth, etc.). Each such wireless communication protocolmay involve transmission of signals at a particular wirelesscommunication signal frequency (e.g., carrier signal frequency,modulation frequency, etc.), such as across one or more wirelessfrequency channels. The components of the payment terminal configured tocommunicate the wireless communication signals may include various typesof hardware and/or software for receiving such wireless communicationsignals from other sources (e.g., NFC devices, payment terminals, etc.).In this regard, the receive circuit of the payment terminal may receivean NFC signal which is based on the NFC carrier signal (e.g., 13.5 MHz).In some embodiments, wireless signals communicated and received at thepayment terminal may include RF noise. In this regard, received NFCsignal may include RF noise, which may mean to increase processingerrors at payment terminal in some embodiments, other types of noise maybe present in the received RF signal, and may be received by thereceiver circuit of the payment terminal for processing. Thereafter,processing may proceed to step 512.

As the 512, the processing unit clock signal may be received by theprocessing unit. In some embodiments, the processing unit clock signalprovided by the clock management unit of the payment terminal may bebased on a signal that will enable sampling of the received NFC signalby the processing unit. As noted above, the processing unit clock signalmay have a third phase in third frequency, which may be configured asdesired to enable sampling of the received NFC signal. As an example,sampling rates for the received NFC signal may be based oncharacteristics of the processing unit (e.g., hardware processinglimitations). After the processing unit has received the processing unitclock signal, processing may proceed to step 514.

At step 514, the processing unit may determine the first phasedifference between the first phase of the switching regulator clocksignal and second phase of the NFC clock signal and/or received noiseand data signals based on these signals. In some embodiments, theprocessing unit (e.g., processing unit 208, a processing unit 312, orsecure processing unit 316) may perform a comparison of the switchingregulator clock signal with the NFC clock signal, such as by executingthe noise management instructions stored in memory. In some embodiments,the processing unit may be configured to determine the first phasedifference by monitoring various types of information, such as anoperating frequency of the one or more switching regulators, noisefrequencies, and an operating frequency of components of the NFC receivecircuit of the payment terminal (e.g., wireless interface 218, NFCinterface 328, etc.). After the first phase difference has beendetermined, processing may proceed to step 516.

At step 516, a frequency difference between first frequency of theswitching regulator clock signal and a second frequency of the NFC clocksignal may be determined. In some embodiments, the processing unit maydetermine a first frequency difference by executing the noise managementinstructions, such as may be stored in memory at the payment terminal.To determine the first frequency difference, in some embodiments, theprocessing unit may compare the first frequency of the switchingregulator clock signal with the second frequency of the NFC clocksignal. In some embodiments, operating frequencies of components of thepayment terminal that receive the switching regulator clock signal andNFC clock signal may be compared and an assumption regarding the secondfrequency difference may be performed in other embodiments. After thefirst frequency difference has been determined, processing may proceedto step 518.

At step 518, a plurality of time periods may be identified at which thenoise is below a threshold. In some embodiments, the processing unit,such as when executing noise management instructions, may be configuredto compare a value associated with a level of RF noise with a thresholdvalue indicative of a threshold amount of RF noise. In some embodiments,the threshold may be determined based on the first phase difference andthe first frequency difference determined at steps 514 and 516 above. Insome embodiments, the processing unit may compare RF noise levels (e.g.,identified by executing noise management instructions stored in memory).If a value of the RF noise falls below the threshold, processing mayproceed to step 520, where the processing unit may identify a timeperiod corresponding to the determination and identify the time periodas a potential time for performing sampling of the received NFC signal.The processing unit may repeat such comparison and determination for adesired number of time periods, until a desired (e.g., minimum) numberof time periods have been identified (e.g., such as an amount thatexceeds a bit error rate threshold for processing received NFC signalsat the payment terminal). If the RF noise exceeds the threshold, at step522, the processing unit may note a corresponding time but will notidentify the time period as one of the plurality of time periods forwhich sampling of the received NFC signal may be possible. For such timeperiods for which an RF noise level is not less than the threshold, theprocessing unit may determine that sampling is not appropriate or thatRF noise levels may result in an amount of bit errors that exceeds adesired amount. After the plurality of possible time periods at which RFnoise does not exceed a threshold has been identified, processing mayproceed to step 524.

At step 524, the received NFC signal may be sampled at the time periodsidentified for which the RF noise level is below the threshold and whichalso corresponds to at least one of the plurality of possible samplingtimes for the received NFC signal. Accordingly, the processing unit maydetermine which time periods match one or more of the plurality ofpossible sampling times previously determined. In this regard, theprocessing unit, by executing the noise management instructions, maydetermine that sampling of the received NFC signal is possible for atleast one of the plurality of time periods based on the possiblesampling times for the received NFC signal identified step 512. In thisregard, the processing unit may sample the received NFC signal at timeperiods when RF noise levels fall below a desired threshold, therebyimproving processing of the received NFC signal and reducing errors. Insome embodiments, the phase and/or frequency of a clock source signalprovided to the processing unit may be modified to correspond toparticular sampling times.

FIG. 6 depicts a non-limiting flow diagram illustrating exemplary stepsof a noise management method for optimizing communications of NFCsignals at a point-of-sale system in accordance with some embodiments ofthe present disclosure. As noted above with regard to FIG. 5, in anembodiment, the steps of FIG. 6 may be directed to and performed by amerchant terminal 110 or customer terminal 112 for coordinatingoperations of components of the payment terminal that may produce RFnoise while a RF communication source of the payment terminal iscommunicating wireless RF signals. For simplicity, the term “paymentterminal” may refer to either or a combination of the merchant terminal110 or customer terminal 112. In addition, payment terminal componentsreferenced herein may refer to corresponding components of either themerchant terminal 110 or customer terminal 112 or various suitablecombinations thereof. Further, the operations below are described in thecontext of communication using RF communications, but it will beunderstood that communication of RF communication signals according toother protocols are possible. It will be further understood that in someembodiments (not depicted in FIG. 6), identification of RF noise sourcesand RF noise frequencies may be performed in other manners, as describedherein.

At step 602 operations the payment terminal may be monitored, such as bya processing unit of the payment terminal. Operations of the wirelesscommunication interfaces of the payment terminal (e.g., wirelesscommunication interface 218 or NFC interface 328) may be monitored todetermine when wireless RF communications occurs at the paymentterminal. In some embodiments, the processing unit (e.g., processingunit 208, 314, or 316) may perform such monitoring by monitoring one ormore clock signals provided to components of the payment terminal. Inparticular, the processing unit may monitor a clock signal provided towireless communication components of the payment terminal, such as maybe used to transmit or receive wireless RF signals. In this regard, theprocessing unit to determine times when wireless communications areoccurring at the payment terminal (e.g., by executing noise managementinstructions stored in memory at the payment terminal).

At step 604, the processing unit to determine whether wireless RFcommunications are occurring at the payment terminal. The processingunit may do so by monitoring the operating frequency of RF communicationsource (e.g. wireless communication interface 218, NFC interface 328,etc.). If wireless RF communication is not currently occurring at thepayment terminal, processing may return to step 602 where operations ofthe payment terminal may continue to be monitored until RF communicationoccurs. If wireless communication is occurring, then the processing mayproceed to step 606.

At step 606, the processing unit may determine that wirelesscommunication is occurring at the payment terminal, such as when a clocksignal provided to one or more components of the payment terminalcomprising a RF communication source has a frequency that corresponds toone or more wireless RF communication frequencies, or when a powerprovided or consumed by a transponder indicates that communications areoccurring. For example, the processing unit may determine that thefrequency of a clock signal provided to the RF communication source iswithin an RF communication frequency. After the processing unit hasdetermined that the RF communication source of the payment terminal iscommunicating wirelessly, processing may then continue to step 608.

At step 608, the processing unit may identify an operating frequency ofan RF noise source at the payment terminal. In some embodiments, the RFnoise source may include one or more components of the payment terminal,such as one or more processing units (e.g., processing unit 208, mainprocessing unit 314, or secured processing unit 316), communicationinterfaces (wireless interface 218, NFC interface 328, user interfaces210, 310, and 318, etc.), user interfaces, or power sources. In someembodiments, a frequency of RF noise emitted by the RF noise sourcewithin payment terminal may correspond to an operating frequency of thecomponent that is the source of RF noise or harmonics thereof. In thisregard, the operating frequency of the RF noise source may be based onor correspond to a clock signal frequency that is provided to the RFnoise source. The clock signal provided to an RF noise source identifiedby the processing unit may have an initial clock signal frequency atwhich the RF noise source may perform standard operations. The RF noisesource may thus perform a set of standard operations when the initialclock signal frequency is provided to the RF noise source. Note that thestandard set of operations may include various types of suitableoperations, and can vary based on the type of component of the paymentterminal that is the source of the RF noise. For example, in someembodiments, when a user interface of the payment terminal (e.g., userinterfaces 210, 310, or 318) is implemented as a touchscreen, thetouchscreen may perform operations at an initial clock frequency, suchas displaying content to a user and receiving touch inputs, or variousother types of operations that may be standard operations of thetouchscreen interface. In some embodiments, the processing unit of thepayment terminal may be configured to provide the initial clockfrequency by default based on hardware, software, or variouscombinations thereof, and thus the touchscreen may perform a standardset of operations under normal circumstances. It is to be understoodthat the standard set of operations performed by the component that isthe RF noise source may vary based on the type of component. After theprocessing unit has identified an operating frequency of the art ofnoise source, processing may proceed to step 610.

At step 610, an operating frequency of the RF noise source may becompared with one or more RF communication frequencies within which theRF communication source of the payment terminal is performing wirelessRF communications. If the operating frequency of the one or more RFnoise sources indicates that none of the one or more noise frequencyfrequencies overlaps with at least a portion of the one or more RFcommunication frequencies, processing may return to step 602 and theprocessing unit may continue to monitor the operation of components ofthe payment terminal for noise. However, if the processing unitdetermines that the one or more RF noise frequencies overlaps with atleast a portion of the one or more RF communication frequencies that thepayment terminal is using to communicate wirelessly, processing mayproceed to step 612.

At step 612, the processing unit may identify a modified clock signalfrequency that the processing unit may provide to the one or more RFnoise sources in order to modify the operating frequency of the RF noisesource, and thereby modify the RF noise frequencies so that the RF noisefrequencies do not overlap with the RF communication frequencies. Forexample, if an operating frequency of an RF noise source causes the RFnoise source to emit RF noise that overlaps a portion of the NFCfrequencies (e.g., at 13.56 MHz modulated at 800 kHz), the processingunit may select an operating frequency for the RF noise source that willmodify the frequencies of the RF noise emitted by the RF noise source.In this regard, a modified clock signal that corresponds to a modifiedoperating frequency of the RF noise source may be identified by theprocessing unit. The processing unit may identify a modified clocksignal for each of the one or more RF noise sources for which it hasdetermined that RF noise frequencies overlap with any portion of the RFcommunication frequencies in use by the payment terminal. In thisregard, the processing unit may provide a modified clock signal at amodified frequency to the one or more RF noise sources based on suchdetermination. After a modified clock signal frequency has been providedto the one or more RF noise resources, and the one or more RF noisesources has received the modified clock frequency, processing mayproceed to step 614.

At step 614, the one or more RF noise sources may perform reduced ormodified operations based on receipt of the modified clock frequencyfrom the processing unit (or in some embodiments, instead of receiving amodified clock frequency). As an example, when an RF noise source isoperating according to an initial clock frequency, the RF noise resourcemay be configured to perform standard operations. In some embodiments,the RF noise source may perform a modified or reduced set of operations,such as by reducing power, performing only a limited subset offunctions, or other similar steps that reduce processing or operationaldemands for the noise source. In some embodiments, the processing unitmay take additional actions when the RF noise sources are operating atthe modified operating frequency. For example, the processing unit mayprovide a particular output to a touchscreen of the payment terminalthat cancels noise (e.g., by interposing known noise signals on the userinterface 210, 310, or 318). After the RF noise source has begunperforming reduced operations, processing may proceed to step 616

At step 616 the processing unit may determine whether the paymentterminal has completed RF communication such that the RF communicationsource is no longer communicating. The processing unit may determinethat the RF communication sources is no longer communicating based onvarious information, such as a clock signal provided to the RFcommunication source, the operating frequency of modifications was,power consumption of wireless interfaces, data received from the RFcommunication sources, etc. If the RF communication source is stillcommunicating, the processing unit may continue to provide the modifiedclock frequency to the RF noise source and/or perform the reduced ormodified operations such that the RF noise source continues to output areduced amount of noise. However, if the processing unit determines thatthe RF communication source is no longer communicating wirelessly,processing may continue to step 618, where the processing unit may ceaseproviding the modified clock frequency to the RF noise source, mayprovide the initial clock frequency. Thereafter, process processing maycontinue to step 620, where the noise source may resume the standard setof operations.

FIG. 7 depicts a non-limiting flow diagram illustrating exemplary stepsof an alternative noise management method for optimizing communicationsof NFC signals at a point-of-sale system in accordance with someembodiments of the present disclosure. The steps of FIG. 7 may becarried out in addition to or in place of the steps described herein fordetermining a time for sampling a received NFC signal at a paymentterminal, for example with regard to FIG. 5. For simplicity, the term“payment terminal” may refer to either or a combination of the merchantterminal 110 or customer terminal 112. In addition, payment terminalcomponents referenced herein may refer to corresponding components ofeither the merchant terminal 110 or customer terminal 112 or varioussuitable combinations thereof. Further, the operations below aredescribed in the context of communication using NFC signals, but it willbe understood that communication of RF communication signals accordingto other protocols are possible.

With regard to FIG. 7, it will be assumed that a clock management unitreceives a clock source signal and is providing a plurality of clocksignals to components of the payment terminal, as described with regardto FIG. 5. In an embodiment, the steps of FIG. 7 may be directed to andperformed by a payment terminal for optimizing receipt of a RF signal bysampling the signal at times when a phase of the received NFC signalmatches a desired phase of the processing unit clock signal. It will befurther understood that in some embodiments (not depicted in FIG. 7),identification of phases at which the RF signal may be sampled in othermanners, as described herein.

At step 702 the processing unit may identify a phase at which a receivedRF signal may be sampled. Although times at which a received RF samplemay be identified based on various information (e.g., processing unitclock frequency as in FIG. 5), in some embodiments, the processing unitmay identify a plurality of possible sampling times based on correlationof a phase of the processing unit clock signal. In this regard, aplurality of possible sampling times may be identified based on thephase of the processing unit clock signal. After a phase of theprocessing unit clock signal at which sampling may be possible has beenidentified, processing may proceed to step 704.

At step 704 a receive circuit of the payment terminal may receive an NFCsignal, such as from a wireless transaction device. In some embodiments,the received NFC signal may have a phase, frequency, amplitude and dutycycle. The processing unit of the payment terminal may be operable tonote a phase of the received NFC signal as the payment terminal'sreceive circuit receives the NFC signal. After the NFC signal has beenreceived, processing may proceed to step 706.

At step 706, the processing unit may determine whether a phase of thereceived NFC signal matches a phase of a processing unit clock signal.In some embodiments, whether the phases of the NFC signal and processingunit clock signal match may be determined based on a difference betweenthe phases, or based on a comparison of whether a phase of the receivedNFC signal is within a threshold difference of the phase of theprocessing unit clock signal. If the phase difference exceeds thethreshold difference, the processing unit may determine that the phasesdo not match, and processing may return to step 702. If the phasedifference is below a threshold difference, the processing unit maydetermine that the phases match, and processing may proceed to step 708.At step 708, the processing unit may sample the received NFC signal forprocessing by the processing unit of the payment terminal.

FIGS. 8A and 8B depict a front perspective view of a user interface of apayment terminal in accordance with some embodiments of the presentdisclosure. The user interface of FIGS. 8A and 8B is depicted as atouchscreen displaying a graphical output. In the embodiment of FIGS. 8Aand 8B, an exemplary user interface is depicted, and it is to beunderstood that although the user interface of FIGS. 8A and 8B may havecertain characteristics and configuration, the user interface isrepresentative of operation at of either a merchant terminal 110 orpayment terminal 112. The exemplary payment terminal of FIGS. 8A and 8Bcomprises user interface 800 and capable of displaying an output 820.The output 820 displayed in FIGS. 8A and 8B is depicted as a graphicaloutput such as may be displayed to a user of the payment terminal, butit will be understood that the output 820 is an exemplary and can bealtered or comprise various types of output which the interface 810 iscapable of providing in other embodiments. In addition, it will beunderstood that even though the payment terminals of FIGS. 8A and 8B maybe depicted as having particular components and implemented in aparticular configuration and arrangement, other combinations arrangementof components are possible.

In addition, the payment terminal of FIGS. 8A and 8B is configured forexchanging wireless messages with a user for completing paymenttransactions wirelessly. In some embodiments, the payment terminal alsomay include components for accomplishing wireless RF communication suchas antenna 824, as well as at least one processing unit (notspecifically shown in FIGS. 8A and 8B), memory for storing instructions(not specifically shown in FIGS. 8A and 8B), a power supply (notspecifically shown in FIGS. 8A and 8B), or any or all of the componentswhich may be included with the various embodiments of a payment terminalas described herein.

As shown in FIG. 8A, interface 810 of the payment terminal isimplemented as a touchscreen interface. The user interface 810 isdepicted as being adjacent (e.g. positioned close in proximity withinthe payment terminal) to a wireless antenna 824 that is capable oftransmitting and receiving wireless RF communication from varioussources (e.g., NFC, Bluetooth, etc.). In the embodiment of FIG. 8A, theinterface 810 is depicted as performing operations with a modified userinterface (e.g., with lower power usage, modified frequency, and/oroffsetting noise characteristics). As noted herein, the components ofthe payment terminal, such as interface 810 may emit RF noise. In thisregard RF noise by interface 810 may cause undesirable errors inprocessing of wireless indication signals. A processing unit of thepayment terminal may execute noise management instructions in order tooptimize operations of the payment terminal and manage noise emitted bycomponents of the payment terminal.

In some embodiments of FIG. 8A, a processing unit of the paymentterminal may execute instructions to determine wireless communicationfrequencies that are in use by the payment terminal. In an exemplaryembodiment, the processing unit may determine the RF communicationfrequency bands based on a RF communication protocol in use by thepayment terminal, such as by determining a clock signal frequencyprovided to or operating frequency for the payment terminal's RFcommunication source. Other techniques and information may be providedto and used by the processing unit to determine that the paymentterminal is communicating wirelessly and identify one or more RFcommunication frequency bands in other embodiments.

In some embodiments, the processing unit of the payment terminal ofFIGS. 8A and 8B likewise may identify one or more RF noise frequenciesbands associated with one or more components of the payment terminal,such as based on a clock frequency provided to one or more componentssuch as the user interface. If an operating frequency corresponds to afrequency of RF noise emitted by the component that will overlap anyportion of the one or more RF communication frequencies, the processingunit may identify a modified or reduced clock frequency to provide tothe component that is the source of the RF noise. In the embodiment ofFIGS. 8A and 8B, the user interface 210 (touchscreen) emits RF noise ata frequency that overlaps a portion of the one or more RF communicationfrequencies. In this regard, the processing unit may note the initialclock signal provided to the user interface 210 and identify a modifiedclock signal to provide that will modify a frequency of RF noise theuser interface is emitting. That is, a modified operating frequency maybe provided that causes an RF noise source to emit RF noise at one ormore frequencies that does not overlap any portion of the one or more RFcommunication frequencies of the payment term.

In an exemplary embodiment, output 820 is depicted as operating at amodified clock frequency, as demonstrated by display of a graphic output820 that has an increased transparency. In some embodiments the noiseemitted by the display may be modified in other manners, such as bymodifying a power supplied to or consumed by the user interface (e.g.,by changing a displayed image to have less contrast, brightness, etc.)or introducing image patterns that result in cancellation or reducednoise. Although such modifications to the graphics graphic 820 displaythe interface may or may not be perceptible to a user viewing theinterface 810, by performing modified operations of the interface,according to the modified operating frequency, RF noise generated duringoperation of the user interface 810 may be reduced, or in someembodiments, modified such that the one or more RF noise frequencies donot overlap with the one or more RF frequencies at which the terminal iscommunicating.

The processing unit may monitor wireless communication at the paymentterminal to determine when the payment terminal is no longercommunicating wirelessly. When the processing unit determines that thepayment terminal is no longer communicating wirelessly at the RFcommunication frequency, the processing unit return the user interface810 to normal operations. In response, as depicted in FIG. 8B, when theuser interface 810 returns to normal operation, the user interface 810may resume standard operations, such that content displayed by the userinterface 810 is provided at a standard operating frequency. Forexample, content 20 may be displayed at a higher contrast, brightness,with more power to display, or at a more suitable frequency for theparticular user interface 810.

The foregoing is merely illustrative of the principles of thisdisclosure and various modifications may be made by those skilled in theart without departing from the scope of this disclosure. The abovedescribed embodiments are presented for purposes of illustration and notof limitation. The present disclosure also can take many forms otherthan those explicitly described herein. Accordingly, it is emphasizedthat this disclosure is not limited to the explicitly disclosed methods,systems, and apparatuses, but is intended to include variations to andmodifications thereof, which are within the spirit of the followingclaims.

As a further example, variations of apparatus or process parameters(e.g., dimensions, configurations, components, process step order, etc.)may be made to further optimize the provided structures, devices andmethods, as shown and described herein. In any event, the structures anddevices, as well as the associated methods, described herein have manyapplications. Therefore, the disclosed subject matter should not belimited to any single embodiment described herein, but rather should beconstrued in breadth and scope in accordance with the appended claims.

1. A method for a near field communication (NFC) device to control oneor more clock signals to reduce interference with NFC signals,comprising: generating, by a clock source of the NFC device, a clocksource signal; receiving, at a clock management unit of the NFC device,the clock source signal; generating, by the clock management unit of theNFC device, a plurality of clock signals, wherein a switching regulatorclock signal of the plurality of clock signals has a first phase and afirst frequency, wherein a NFC clock signal of the plurality of clocksignals has a second phase and a second frequency, and wherein aprocessing unit clock signal of the plurality of clock signals has athird phase and a third frequency; receiving, by one or more switchingregulators of the NFC device, the switching regulator clock signal,wherein the one or more switching regulators emit RF noise based on thefirst phase and first frequency; receiving, by a processing unit of theNFC device, the NFC clock signal, wherein a transmitted NFC carriersignal is based on the second phase and the second frequency; receiving,by a receive circuit of the NFC device, a received NFC signal, whereinthe received NFC signal is based on the NFC carrier signal, and whereinthe received NFC signal includes the RF noise; receiving, by theprocessing unit, the processing unit clock signal, wherein a pluralityof possible sampling times for the received NFC signal is based on thethird phase and the third frequency; determining, by the processingunit, a first phase difference between the first phase of the switchingregulator clock signal and the second phase of the NFC clock signal;determining, by the processing unit, a first frequency differencebetween the first frequency of the switching regulator clock signal andthe second frequency of the NFC clock signal; identifying, by theprocessing unit, a plurality of sampling times based on the first phasedifference and the first frequency difference; and sampling, by theprocessing unit, the NFC signal at the plurality of sampling times. 2.The method of claim 1, further comprising: determining, at theprocessing unit, a phase of the RF noise; determining, at the processingunit, a phase offset between the phase of the RF noise and the secondphase of the NFC clock signal; providing, by the processing unit, asignal to the clock management unit indicative of the phase offset; andmodifying, at the clock management unit, the plurality of clock signalsbased on the phase offset, wherein the first phase, the second phase,and third phase are modified based on the phase offset.
 3. The method ofclaim 2, wherein the phase offset is based on the first phasedifference.
 4. The method of claim 1, wherein the first frequency andthe second frequency are selected such that harmonics of the firstfrequency do not interfere with the second frequency.
 5. The method ofclaim 1, further comprising: providing, by the processing unit, acontrol signal to one or more programmable noise filters based on thefirst phase difference and first frequency difference, wherein thecontrol signal modifies a filtering parameter of the one or moreprogrammable noise filters; and filtering, by the one or moreprogrammable noise filters, the RF noise of the received NFC signal. 6.A method for a wireless communication device to control one or moreclock signals to optimize the communication of wireless signals,comprising: generating, by a clock source of the wireless communicationdevice, a clock source signal; receiving, at a clock management unit ofthe wireless communication device, the clock source signal; generating,by the clock management unit of the wireless communication device, aplurality of clock signals, wherein a noise source clock signal of theplurality of clock signals has a first phase and a first frequency andwherein a wireless clock signal of the plurality of clock signals has asecond phase and a second frequency; receiving, by a noise source of thewireless communication device, the noise source clock signal, whereinthe noise source emits RF noise based on the first phase and the firstfrequency; receiving, by a wireless source of the wireless communicationdevice, the wireless clock signal; communicating, by the wireless sourceof the wireless communication device, a wireless signal based on thesecond phase and the second frequency; comparing, by the wirelesscommunication device, the RF noise with the communicated wirelesssignal; and modifying, by the clock management unit, the first phase orthe first frequency based on the comparing.
 7. The method of claim 6,wherein the wireless communication device comprises a near fieldcommunication (NFC) device, the wireless source comprises a NFC source,and the communicated wireless signal comprises a NFC signal.
 8. Themethod of claim 7, wherein the comparing is based on a phase of the RFnoise and a phase of the NFC signal.
 9. The method of claim 7, furthercomprising receiving, by the NFC source, a modulated version of the NFCsignal, wherein the comparing is based on a phase of the RF noise and aphase of the modulated version of the NFC signal.
 10. The method ofclaim 6, wherein the noise source comprises a switching regulator. 11.The method of claim 6, wherein a processing unit clock signal of theplurality of clock signals has a third phase and a third frequency, andwherein a sampling time of a processing unit for the wireless signal isbased on the comparing, the third phase, and the third frequency. 12.The method of claim 11, further comprising modifying, by the clockmanagement unit, the third phase or the third frequency based on thecomparing.
 13. The method of claim 6, further comprising: determining,by the wireless communication device, a phase of the RF noise; anddetermining, by the wireless communication device, a phase of thewireless signal, wherein the comparing is based on the comparison of thephase of the RF noise and the phase of the wireless signal.
 14. Themethod of claim 6, wherein the first frequency and the second frequencyare selected such that harmonics of the first frequency do not interferewith the second frequency.
 15. The method of claim 6, furthercomprising: providing, by the wireless communication device, a controlsignal to one or more programmable noise filters of the wirelesscommunication device based on the comparing, wherein the control signalmodifies a filtering parameter of the one or more programmable noisefilters; and filtering, by the one or more programmable noise filters,the RF noise.
 16. A wireless communication device for controlling one ormore clock signals to optimize the communication of wireless signals,comprising: a clock source configured to generate a clock source signal;a clock management unit configured to receive the clock source signalconfigured to generate a plurality of clock signals, wherein a noisesource clock signal of the plurality of clock signals has a first phaseand a first frequency and wherein a wireless clock signal of theplurality of clock signals has a second phase and a second frequency; anoise source configured to receive the noise source clock signal,wherein the noise source emits RF noise based on the first phase and thefirst frequency; and a wireless source configured to receive thewireless clock signal, wherein the wireless source is configured tocommunicate a wireless signal based on the second phase and the secondfrequency, wherein the wireless communication device is configured tocompare the RF noise and the communicated wireless signal, and whereinthe clock management unit is further configured to modify the firstphase or the first frequency based on the comparison.
 17. The device ofclaim 16, wherein the wireless communication device comprises a nearfield communication (NFC) device, the wireless source comprises a NFCsource, and the communicated wireless signal comprises a NFC signal. 18.The device of claim 17, wherein the wireless communication device isconfigured to compare a phase of the RF noise with a phase of the NFCsignal.
 19. The device of claim 17, further comprising receiving, by theNFC source, a modulated version of the NFC signal, wherein the comparingis based on a phase of the RF noise and a phase of the modulated versionof the NFC signal.
 20. The device of claim 16, wherein the noise sourcecomprises a switching regulator.
 21. The device of claim 16, wherein aprocessing unit clock signal of the plurality of clock signals has athird phase and a third frequency, and wherein a sampling time of aprocessing unit for the wireless signal is based on the comparing, thethird phase, and the third frequency.
 22. The device of claim 21,wherein the clock management unit is further configured to modify thethird phase or the third frequency based on the comparison of the RFnoise and the communicated wireless signal by the wireless communicationdevice.
 23. The device of claim 16, wherein the wireless communicationdevice is further configured to determine a phase of the RF noise and aphase of the wireless signal, and wherein the wireless communicationdevice is further configured to compare the phase of the RF noise andthe phase of the wireless signal.
 24. The device of claim 16, whereinthe first frequency and the second frequency are selected such thatharmonics of the first frequency do not interfere with the secondfrequency.
 25. The device of claim 16, wherein the wirelesscommunication device is further configured to provide a control signalto one or more programmable noise filters of the wireless communicationdevice based on the comparison of the RF noise and the communicatedwireless signal, wherein the control signal modifies a filteringparameter of the one or more programmable noise filters, and wherein theone or more programmable noise filters is configured to filter the RFnoise.
 26. A non-transitory computer-readable storage medium comprisinginstructions stored therein, which when executed by one or moreprocessors, cause the one or more processing units to perform operationscomprising: generating a clock source signal by a clock source of awireless communication device; receiving the clock source signal at aclock management unit of the wireless communication device; generating aplurality of clock signals by the clock management unit, wherein a noisesource clock signal of the plurality of clock signals has a first phaseand a first frequency and wherein a wireless clock signal of theplurality of clock signals has a second phase and a second frequency;receiving the noise source clock signal by a noise source of thewireless communication device, wherein the noise source of the wirelesscommunication device emits RF noise based on the first phase and thefirst frequency; receiving the wireless clock signal by a wirelesssource of the wireless communication device; communicating a wirelesssignal by the wireless source of the wireless communication device basedon the second phase and the second frequency; comparing the RF noisewith the communicated wireless signal; and modifying the first phase orthe first frequency based on the comparing.
 27. The non-transitorycomputer-readable storage medium of claim 26, wherein the wirelesscommunication device comprises a near field communication (NFC) device,the wireless source comprises a NFC source, and the communicatedwireless signal comprises a NFC signal.
 28. The non-transitorycomputer-readable storage medium of claim 27, wherein the comparison ofthe RF noise with the communicated wireless signal is based on a phaseof the RF noise and a phase of the NFC signal.
 29. The non-transitorycomputer-readable storage medium of claim 27, wherein the instructionsfurther comprise instructions that cause the one or more processors toperform operations comprising: receiving a modulated version of the NFCsignal by the NFC source, wherein the comparison of the RF noise withthe communicated wireless signal is based on a phase of the RF noise anda phase of the modulated version of the NFC signal.
 30. Thenon-transitory computer-readable storage medium of claim 26, wherein thefirst frequency and the second frequency are selected such thatharmonics of the first frequency do not interfere with the secondfrequency.
 31. A device for communicating RF signals, comprising: aclock source configured to generate a clock source signal; a clockmanagement unit configured to receive the clock source signal andconfigured to generate a plurality of clock signals, wherein a noisesource clock signal of the plurality of clock signals has a phase and afrequency; a noise source configured to receive the noise source clocksignal, wherein the noise source emits RF noise based on the first phaseand the first frequency; and a circuit configured to communicate an RFsignal, wherein the device is configured to determine at least one valueindicating an extent to which the RF noise interferes with the RFsignal, and wherein the clock management unit is further configured tomodify the phase or the frequency based on the at least one value. 32.The device of claim 31, wherein the device is configured to determinethe at least one value by comparing the RF noise and the RF signal. 33.The device of claim 31, wherein the device is configured to compare theat least one value to a threshold and to determine whether to modify thefirst phase or the first frequency based on a comparison of the at leastone value to the threshold.
 34. The device of claim 31, wherein the RFsignal is a wireless signal.